Z shell
The Z shell is a shell and a command-line interpreter for shell scripts. Zsh mostly maintains the Bourne shell's syntax and behavior, but makes several changes breaking from the POSIX standard and substantially more features.
Zsh was created by Paul Falstad in 1990 while he was a student at Princeton University. It combines features from both ksh and tcsh, offering functionality such as programmable command-line completion, extended file globbing, improved variable/array handling, and themeable prompts.
Zsh is available for Microsoft Windows as part of the UnxUtils collection and has been adopted as the default interactive shell for macOS, Deepin, and Kali Linux. The "Oh My Zsh" user community website provides a platform for third-party plug-ins and themes, featuring a large and active contributor base.
History
Paul Falstad wrote the first version of Zsh in 1990 while a student at Princeton University. The name zsh derives from the name of Zhong Shao, a teaching assistant at Princeton University. Falstad regarded Shao's login, "zsh", as a good name for a shell.Zsh was at first intended to be a subset of csh for the Amiga, but expanded far beyond that. By the time of the release of version 1.0 in 1990 the aim was to be a cross between ksh and tcsh a powerful "command and programming language" that is well-designed and logical, but also built for humans, with all the neat features like spell checking, login/logout watching and termcap support that were "probably too weird to make it into an AT&T product".
Zsh is available for Microsoft Windows as part of the UnxUtils collection of native Win32 ports of common GNU Unix-like utilities.
In 2019, macOS Catalina adopted Zsh as the default login shell, replacing the GPLv2 licensed version of Bash, and when Bash is run interactively on Catalina, a warning is shown by default.
In 2020, Kali Linux adopted Zsh as the default shell since its 2020.4 release.
Features
Features include:- Programmable command-line completion that can help the user type both options and arguments for most used commands, with out-of-the-box support for several hundred commands
- Sharing of command history among all running shells
- Extended file globbing allows file specification without needing to run an external program such as find
- Improved variable/array handling
- Editing of multi-line commands in a single buffer
- Spelling correction and autofill of command names
- Various compatibility modes, e.g. Zsh can pretend to be a Bourne shell when run as
/bin/sh - Themeable prompts, including the ability to put prompt information on the right side of the screen and have it auto-hide when typing a long command
- Loadable modules, providing among other things: full TCP and Unix domain socket controls, an FTP client, and extended math functions.
- The built-in
wherecommand. Works like thewhichcommand but shows all locations of the target command in the directories specified in$PATHrather than only the one that will be used. - Named directories. This allows the user to set up shortcuts such as
~mydir, which then behave the way~and~userdo. - Widgets. Both built and implemented by ordinary functions widgets can be bound to hotkeys.
- Function autoloading. A performance optimization for function that might be pre-loaded and run on demand. The intent of loading functions as separate file is also to support function features across different zsh versions.